diff --git a/debian/changelog b/debian/changelog
index c5cc469d..8392d81a 100644
--- a/debian/changelog
+++ b/debian/changelog
@@ -1,3 +1,12 @@
+debian-cd (3.1.31) UNRELEASED; urgency=medium
+
+  [ Steve McIntyre ]
+  * tools/generate_di_list: Only include kernel udebs for the highest
+    ABI we know about. Don't waste space on new installation media
+    with older udebs from the archive.
+
+ -- Steve McIntyre <93sam@debian.org>  Sun, 27 Sep 2020 01:10:07 +0100
+
 debian-cd (3.1.30) unstable; urgency=medium
 
   [ Steve McIntyre ]
diff --git a/tools/generate_di_list b/tools/generate_di_list
index 3ab3c723..d7e29707 100755
--- a/tools/generate_di_list
+++ b/tools/generate_di_list
@@ -1,12 +1,18 @@
-#!/usr/bin/perl -w
+#!/usr/bin/perl
 # Generate a list of packages required for debian-installer
 # This script makes use of the following variables that need to be preset:
 # MIRROR, DI_CODENAME, BASEDIR
+
+use strict;
+use warnings;
+
 die "Missing \$MIRROR variable" unless $ENV{MIRROR};
 die "Missing \$DI_CODENAME variable" unless $ENV{DI_CODENAME};
 die "Missing \$BASEDIR variable" unless $ENV{BASEDIR};
 die "Missing \$ARCHES variable" unless $ENV{ARCHES};
 
+my $catz = $ENV{BASEDIR} . "/tools/catz";
+
 # Early exit if we're building a source-only CD
 exit 0 if $ENV{ARCHES} =~ /^\s*source\s*$/;
 
@@ -38,6 +44,33 @@ print OUT << "EOF";
  */
 EOF
 
+sub di_ker_abi_to_number ($$$$) {
+    # Make up a version we can compare sensibly from
+    # the version and ABI
+    my $maj = shift;
+    my $min = shift;
+    my $patch = shift;
+    my $abi = shift;
+    my $kernel_ver = ($maj * 1000000000)
+	+ ($min * 1000000)
+	+ ($patch * 1000)
+	+ $abi;
+    return $kernel_ver;
+}
+
+sub number_to_di_ker_abi ($) {
+    # Convert back to a useful string
+    my $num = shift;
+    my $maj = int($num / 1000000000);
+    $num -= ($maj * 1000000000);
+    my $min = int($num / 1000000);
+    $num -= ($min * 1000000);
+    my $patch = int($num / 1000);
+    $num -= ($patch * 1000);
+    my $abi = $num;
+    return "$maj.$min.$patch-$abi";
+}
+
 my @common_excludes = read_exclude("exclude-udebs");
 my $mirror_path = "$ENV{MIRROR}/dists/$ENV{DI_CODENAME}";
 my @components = qw(main);
@@ -65,18 +98,71 @@ foreach my $arch (@ARCHES) {
         push @exclude, read_exclude("exclude-udebs-$arch")
             if -e exclude_path("exclude-udebs-$arch");
 
-	if (-f $pgz) {
-	    foreach my $udeb (map { chomp; $_ } `zcat $pgz | awk '/^Package:/ {print \$2}'`) {
-		$output .= "$udeb\n" unless grep { $udeb =~ /^${_}$/ } @exclude;
-	    }
-	} elsif (-f $pxz) {
-	    foreach my $udeb (map { chomp; $_ } `xzcat $pxz | awk '/^Package:/ {print \$2}'`) {
-		$output .= "$udeb\n" unless grep { $udeb =~ /^${_}$/ } @exclude;
-	    }
-	} else {
+	my $pz = $pgz;
+	if (! -f $pz) {
+	    $pz = $pxz;
+	}
+	if (! -f $pz) {
             print "Missing package file for $arch/$component.\n";
             next;
-        }
+	}
+
+	# Two passes here
+	# First, need to find the highest kernel ABI in the archive
+	# Next, list all the udebs that:
+	#   1. are not otherwise excluded
+	#   2. are not kernel driver udebs, OR
+	#      are kernel driver udebs with the right kernel ABI
+
+	unless ( open (PZ, "$catz $pz |") ) {
+	    warn "failed to read package file $pz: $1";
+	    next;
+	}
+
+	my @output_udebs;
+	my %driver_udebs;
+	my $highest_kernel_ver = 0;
+
+	while (defined (my $line = <PZ>)) {
+	    chomp $line;
+	    if ($line =~ m/^Package: (\S+)/) {
+		my $udeb = $1;
+		if (grep { $udeb =~ /^${_}$/ } @exclude) {
+		    next;
+		}
+		if ($udeb =~ m/-modules-([0-9]*)\.([0-9]*)\.([0-9]*)-(\d+)-.*-di/) {
+		    my $kernel_ver = di_ker_abi_to_number($1, $2, $3, $4);
+		    if ($kernel_ver > $highest_kernel_ver) {
+			$highest_kernel_ver = $kernel_ver;
+		    }
+		    # Append this driver udeb to a list for that kernel_ver
+		    push(@{ $driver_udebs{$kernel_ver} }, $udeb);
+		} else {
+		    #print "found non-driver udeb $udeb\n";
+		    push @output_udebs, $udeb;
+		}
+	    }
+	}
+	close PZ;
+	$output .= "/* First, generic udebs */\n";
+	foreach my $udeb (@output_udebs) {
+	    $output .= "$udeb\n";
+	}
+	my $num_this_abi = scalar (@{ $driver_udebs{$highest_kernel_ver}});
+	$output .= "/* Next: $num_this_abi udebs for kernel/ABI version ";
+	$output .= number_to_di_ker_abi($highest_kernel_ver);
+	$output .= " */\n";
+	foreach my $udeb (@{ $driver_udebs{$highest_kernel_ver}}) {
+	    $output .= "$udeb\n";
+	}
+	foreach my $key (keys (%driver_udebs)) {
+	    if ($key != $highest_kernel_ver) {
+		$num_this_abi = scalar (@{ $driver_udebs{$key}});
+		$output .= "/* IGNORING $num_this_abi udebs for kernel/ABI version ";
+		$output .= number_to_di_ker_abi($key);
+		$output .= " */\n";
+	    }
+	}
     }
 
     next unless $output;